Scientists investigate dolphin deaths on Texas coast

Scientists are trying to find out why 119 bottlenose dolphins became stranded and died along the Texas coast in recent months, looking at possibilities ranging from algae blooms to oil pollution.

The National Oceanic and Atmospheric Administration has declared that the stranding of 123 dolphins in Texas between November and March was an “unusual mortality event” and called for the investigation.

Heidi Whitehead, state operations coordinator of the Texas Marine Mammal Stranding Network, which is involved in the investigation, said on Tuesday that four dolphins have survived and are being rehabilitated.

“Beginning in November of 2011, we started seeing a higher number than average of marine mammal strandings on the Texas coastline,” Whitehead said. “There is no cause that we have ruled out.”

Possible causes include algae blooms and pollution such as oil, she said. The strandings coincided with a harmful algal bloom in southern Texas, according to NOAA, and the 2010 Deepwater Horizon disaster in the Gulf of Mexico was the worst offshore oil spill in U.S. history.

But investigators may never know what caused the die-off.

This is the fifth unusual mortality event in Texas and the first since 2008, according to NOAA. All involved bottlenose dolphins.

This die-off affected only dolphins, “but there have been numerous fish kills and bird die-offs in the same geographic area,” the NOAA website said.